import json

import boto3

from app.config import BroadcastProvider

# The variable names in this file have specific meaning in a CAP message
#
# identifier is a unique field for each CAP message
#
# headline is a field which we are not sure if we will use
#
# description is the body of the message

# areas is a list of dicts, with the following items
# * description is a string which populates the areaDesc field
# * polygon is a list of lat/long pairs
#
# previous_provider_messages is a whitespace separated list of message identifiers
# where each identifier is a previous sent message
# ie a Cancel message would have a unique identifier but have the identifier of
#    the preceeding Alert message in the previous_provider_messages field


class CBCProxyException(Exception):
    pass


# Noop = no operation
class CBCProxyNoopClient:

    def init_app(self, app):
        pass

    def send_canary(
        self,
        identifier,
    ):
        pass

    def send_link_test(
        self,
        identifier,
    ):
        pass

    def create_and_send_broadcast(
        self,
        identifier, headline, description, areas,
        sent, expires,
    ):
        pass

    # We have not implementated updating a broadcast
    def update_and_send_broadcast(
        self,
        identifier, previous_provider_messages, headline, description, areas,
        sent, expires,
    ):
        pass

    # We have not implemented cancelling a broadcast
    def cancel_broadcast(
        self,
        identifier, previous_provider_messages, headline, description, areas,
        sent, expires,
    ):
        pass


class CBCProxyClient:
    provider_function_name_map = {
        BroadcastProvider.EE: 'bt-ee-1-proxy',
    }

    def init_app(self, app):
        self._lambda_client = boto3.client(
            'lambda',
            region_name='eu-west-2',
            aws_access_key_id=app.config['CBC_PROXY_AWS_ACCESS_KEY_ID'],
            aws_secret_access_key=app.config['CBC_PROXY_AWS_SECRET_ACCESS_KEY'],
        )

    def _invoke_lambda(self, function_name, payload):
        payload_bytes = bytes(json.dumps(payload), encoding='utf8')

        result = self._lambda_client.invoke(
            FunctionName=function_name,
            InvocationType='RequestResponse',
            Payload=payload_bytes,
        )

        if result['StatusCode'] > 299:
            raise CBCProxyException('Could not invoke lambda')

        if 'FunctionError' in result:
            raise CBCProxyException('Function exited with unhandled exception')

        return result

    def send_canary(
        self,
        identifier,
    ):
        """
        canary - a specific lambda that does not connect to a provider, but just confirms the connectivity between
        Notify and the CBC proxy AWS account
        """
        self._invoke_lambda(function_name='canary', payload={'identifier': identifier})

    def send_link_test(
        self,
        identifier,
    ):
        """
        link test - open up a connection to a specific provider, and send them an xml payload with a <msgType> of
        test.
        """
        payload = {'message_type': 'test', 'identifier': identifier}

        self._invoke_lambda(function_name='bt-ee-1-proxy', payload=payload)

    def create_and_send_broadcast(
        self,
        identifier, headline, description, areas,
        sent, expires,
    ):
        payload = {
            'message_type': 'alert',
            'identifier': identifier,
            'headline': headline,
            'description': description,
            'areas': areas,
            'sent': sent,
            'expires': expires,
        }
        self._invoke_lambda(function_name='bt-ee-1-proxy', payload=payload)

    # We have not implementated updating a broadcast
    def update_and_send_broadcast(
        self,
        identifier, previous_provider_messages, headline, description, areas,
        sent, expires,
    ):
        pass

    # We have not implemented cancelling a broadcast
    def cancel_broadcast(
        self,
        identifier, previous_provider_messages, headline, description, areas,
        sent, expires,
    ):
        pass